NANOINTERACT Sintesi della relazione

Final Report Summary - NANOINTERACT (Development of a platform and toolkit for understanding interactions between nanoparticles and the living world)

The responsible development and implementation of nanotechnology is recognised as being critical to recouping the significant investment in Europe into nanoscience and nanotechnologies over the last decade. Nanotechnologies are considered an enabling technology since their potential applications are so widespread. Indeed several hundred consumer products claiming to contain nanotechnologies are already available. Central to achieving this vision is ensuring that nanotechnologies do not cause inadvertent harm to human or environmental health at any stage of their life cycle.

Thus, the overarching objective of the NANOINTERACT project was to create a firm scientific and technical basis to enable understanding and potential prediction of likely biological impacts of engineered nanoscale particulates. The project sought to connect the uptake and biodistribution of nanoparticles by cells with the nature of the particles in biological solution and with the functional impacts of the various nanoparticles as a result of their presence in specific subcellular compartments.

More specifically, the NANOITERACT objectives were to: 1. establish experimental protocols for every aspect of the study of nanoparticle interaction with cells and several types of aquatic plants and organisms, ensuring complete reproducibility; 2. understand the effect of adsorbed protein on nanoparticle stability and nanoparticles on protein conformation and function, ultimately connecting this to biological impacts; 3. connect cellular location of nanoparticles with intracellular and intercellular disrupted processes; 4. combine these results, along with the expertise from diverse disciplines, to point towards a 'standard approach to nanotoxicology'.

The underpinning hypothesis of the project was that uptake was mediated by the nature of the protein, or biomolecule, corona that formed around nanoparticles immediately upon contact with biological fluids, including cell culture media or the natural organic matter that was dissolved in river water. As such, very considerable effort was devoted to understanding how these interactions affected the available nanoparticle dose and the dispersion evolution with time, under a range of biological conditions and over a variety of both short and long exposure durations.

During the last period of the project, each of the work packages focused on assessing the impacts of nanomaterials, safe in the knowledge that the nanoparticle dispersion and their evolution was assessed under the appropriate exposure conditions and timescales. A range of different methodologies were applied in a time-resolved manner to follow the lifetime of such biomolecular 'coronas' both in situ and isolated from the excess plasma. It was found, for several nanomaterial types, that blood plasma derived coronas were sufficiently long lived and that they, rather than the nanomaterial surface, were likely to be what the cell saw. An important finding was that, although the composition of different particle like protein organisations in biological media might vary, a high level of reproducibility of the populations of different organisations could be achieved if well designed dispersion protocols were used.

Furthermore, extensive studies with silicon dioxide (SiO2) nanoparticles from a range of different sources showed that, in general, they were not cytotoxic, although some exception related to stabilisers such as ethylene and glycol did emerge. The results suggested that the widespread application of amorphous silica nanoparticles might not be without any health hazards. Long term exposure of high concentrations of these nanoparticles to humans could potentially result in particle accumulation and, subsequently, induce acute or chronic toxicity including the embryo, suggesting that more research was needed on this aspect.

In addition, the central role played by the nanoparticle protein corona in mediating the interaction of nanoparticles with living systems was confirmed. It was therefore demonstrated that the nature of the protein corona determined the uptake behaviour, i.e. its mechanism, kinetics and localisation. The intracellular concentration, which was essentially the dose, of nanoparticles was affected by serum heat inactivation and complement depletion. The amount of adsorbed proteins in the long-lived (hard) corona was affected by heat inactivation and correlated with nanoparticle uptake, with a more protein rich corona leading to decreased particle uptake by cells.

While it was hard to predict the long-term impact of the performed research, it was clear that a major element of this impact would be an understanding of how to carry out durable, reproducible, collaborative research in the field of nanosafety assessment. It also seemed likely that the nature and role of the protein corona would be clarified and could become a standard characterisation step for determining nanoparticle impacts.